HDL

edalize
An abstraction library for interfacing EDA tools

fusesoc
Package manager and build abstraction tool for FPGA/ASIC development

migen
A Python toolbox for building complex digital hardware

MyHDL
Python as a hardware description and verification language

nMigen
A refreshed Python toolbox for building complex digital hardware

PipelineC
Open source C-like hardware description language with high-level-synthesis-like automatic pipelining and several other real life design inspired features.

Silice
Silice is an open source language that simplifies writing algorithms fully exploiting FPGA architectures